Staple drive assembly

ABSTRACT

A staple drive assembly includes an actuation sled and at least one staple pusher. The staple drive assembly is adapted to fit within a staple cartridge having a plurality of staples and a corresponding number of retention slots. The at least one staple pusher includes at least one pusher plate for releasably engaging a backspan of a staple. The staple pusher may include a plurality of pusher plates that may be laterally and longitudinally spaced apart. An actuation member has at least one angled camming surface for engaging a complimentary angled surface of the at least one staple pusher. Camming engagement between the actuation member and the at least one staple pusher causes vertical movement of the at least one staple pusher. Lateral and longitudinal offset of the actuation member camming surfaces and the corresponding staple pusher following surfaces improves stability and control of the staple pusher during firing.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/242,761, filed Oct. 4, 2005, the entire contents of whichare incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to stapling apparatus. More particularly,the present disclosure relates to a staple drive assembly for use in astaple cartridge of a stapling apparatus.

2. Background of Related Art

Surgical stapling apparatus are widely used in surgical procedures tofasten body tissue quickly and efficiently by driving fasteners, orstaples into the tissue. In certain types of stapling apparatus, a drivemember moves transversely to the direction the staples are to be driven.Typically, such stapling apparatus employ a number of staple pusherelements located in grooved slots of a staple cartridge and arranged endto end in rows. Under normal operation, the transversely moving drivemember contacts a cam member on the staple pusher thereby pushing thestaple pusher vertically in the grooved slot. The staple pushertransmits linear motion from the drive member to the staples. The rowsof staples are thereby driven into the body tissue to be fastened.

Several issues arise in designing staple pushers for driving one or moresurgical staples. If the forces applied to the staple pusher are noteffectively balanced, there is a tendency for the staple pusher to twistwithin the grooved slot and/or bind against the walls of the groovedslot. Additionally, a single point of contact between the actuation sledand the staple pusher may create a rocking point on the staple pusherwhich can cause the staple pusher to exit the staple cartridge in anunbalanced manner which may result in non-uniform staple formation.Moreover, staple pushers for driving a plurality of staples may offermore resistance to longitudinal movement of the drive member. It isdesirable that the staple pusher permit application of a relativelysmooth ejection force throughout the operation of the drive member. Itis also desirable that the stapling apparatus form a plurality offinished staples having a substantially uniform configuration.

Various staple pusher and cam bar arrangements are known. See, forexample, U.S. Pat. Nos. 4,955,959; 4,978,049; 5,395,034; 5,630,541;5,662,258; 6,131,789 and D278,081.

SUMMARY

The present disclosure is directed towards a staple drive assembly foruse in a staple cartridge. The staple drive assembly includes anactuation sled and at least one staple pusher. The staple cartridgeincludes a tissue contacting surface having a number of retention slotswherein each retention slot is adapted for releasably receiving astaple. The staple cartridge may include a guide channel extending froma proximal portion to a distal portion along its longitudinal axis. Inone embodiment, the staple cartridge is adapted for use in a surgicalstapler having a drive mechanism.

The actuation sled includes a base, at least one camming member and aguide member. Each camming member includes a first or leading cam wedgeand a second or trailing cam wedge. The leading and trailing cam wedgesare laterally and longitudinally spaced apart from one another. Spacingof the cam wedges apart, both laterally and longitudinally, creates asituation in which the staple pusher is contacted at points offset intwo planes so that as the staple pusher is driven, it is controlled anddriven substantially perpendicular to the tissue plane of the cartridgewithout rocking in any direction which would compromise driving thestaple perpendicular to the tissue contacting plane. Additionally, eachcam wedge includes a first drive face and a second drive face. In oneembodiment, the first drive faces form first drive angles with respectto the base and second drive faces form second drive angles with respectto a plane that is substantially parallel to the base. The guide memberis adapted for slidably engaging the guide channel for aligning andguiding the actuation sled as it translates through the staplecartridge. In one embodiment, first drive faces are oriented such thatfirst drive angles may be in a range of about 30° to about 40° while thesecond drive faces are oriented such that second drive angles may be ina range of about 15° to about 25°.

Each staple pusher includes at least one pusher plate and at least onecam member. In one embodiment, each staple pusher includes three pusherplates and two cam members. In an alternate embodiment, each staplepusher includes one pusher plate and two cam members. In a furtherembodiment, each staple pusher includes two pusher plates and two cammembers. First and second cam members are adapted for slidably engagingone of the cam assemblies of the actuation sled. Each cam memberincludes first and second cam surfaces that define respective first andsecond engagement or receiving angles that are complementary to thefirst and second drive angles. In one embodiment, the first receivingangles may be in a range of about 15° to about 55° while the secondreceiving angles may be in a range of about 5° to about 35°. In anotherembodiment, the first receiving angles may be in a range of about 25° toabout 45° while the second receiving angles may be in a range of about10° to about 30°. In a further embodiment, the first receiving angle maybe in the range of about 30° to about 40° while the second receivingangle may be in the range of about 15° to about 25°. The first andsecond cam members are longitudinally and laterally spaced apart tocomplement the arrangement of the leading and trailing cam wedges of theactuation sled.

Distal travel of the actuation sled through the staple cartridge causesthe sequential engagement of the actuation sled and the staple pushersdisposed in the staple cartridge. As the actuation sled moves along thelongitudinal axis of the staple cartridge, the first drive facesslidably engage the first cam surfaces thereby urging each staple pusherin a generally vertical direction. As the actuation sled continues tomove distally, the second drive faces slidably engage the second camsurfaces of each staple pusher to continue to drive each staple pusherin a generally vertical direction while the first drive faces disengagefrom the first cam surfaces. Each camming member contacts each staplepusher in at least two longitudinally spaced locations for urging eachstaple pusher vertically. This longitudinally staggered arrangement ofthe drive faces in cooperation with the complementary staggeredarrangement of the cam members maximizes the longitudinal stability ofthe staple pusher as it moves vertically. Additionally, the first andsecond drive angles in cooperation with the complementary first andsecond receiving angles contribute to the improved longitudinalstability of each staple pusher.

In another embodiment of the present disclosure, an actuation sledincludes substantially the same or similar components, but the first andsecond drive angles may be in a range of about 5° to about 35° while thesecond drive angles may be in a range of about 20° to about 55°. Inanother embodiment, first drive angles may be in a range of about 10° toabout 30° while second drive angles may be in a range of about 25° toabout 45°. In a further embodiment, first drive angles may be in a rangeof about 15° to about 25° while second drive angles may be in a range ofabout 30° to about 40°. During distal movement of the actuation sled,the first drive faces slidably engage the second cam surfaces urgingeach staple pusher in a generally vertical direction. As the actuationsled continues to move distally, the second drive faces engage first camsurfaces as the first drive faces disengage from the second camsurfaces. Applicants have found that providing a cam wedges with a firstdrive surface angle which is less than the second drive angle provides asmooth firing stroke. Similar to the previous embodiment, longitudinalstability of the staple pusher is maximized by the longitudinallystaggered (i.e. spaced apart) cam members in cooperation with thecomplementarily staggered cam wedges. In addition, when the first driveangle is less than the second drive angle, the staple pusher contactsboth drive surfaces as contact with the staple pusher transitions fromcontacting one drive surface to the other drive surface.

In a further embodiment of the present disclosure, an actuation sled isdisclosed that includes the same or substantially similar components. Inthis embodiment, the actuation sled includes first and second cammingmembers, a base, and a guide member. Each camming member furtherincludes first and second cam wedges that are longitudinally spacedapart and define a drive angle with respect to the base. The first andsecond cam wedges of each camming member are laterally spaced apart aswell.

Another embodiment of the present disclosure includes an actuation sledthat has the same or substantially similar components. According to thisembodiment, the actuation sled includes first and second cammingmembers, a base, and a guide member. Each camming member furtherincludes first and second cam wedges that are laterally spaced apartfrom each other and define a plurality of drive angles with respect tothe base. In particular, each cam wedge defines a first set of driveangles that may be in the range of about 15° to about 25° and a secondset of drive angles that may be in the range of about 26° to about 36°.In another embodiment, each cam wedge defines a first set of driveangles that may be in the range of about 17° to about 23° and a secondset of drive angles that may be in the range of about 28° to about 34°.In a further embodiment, each cam wedge defines a first set of driveangles that may be in the range of about 19° to about 21° and a secondset of drive angles that may be in the range of about 30° to about 32°.

In an alternate embodiment of the present disclosure, an actuation sledis described having the same or substantially similar components.According to this embodiment, the actuation sled includes first andsecond camming members, a base, and a guide member. Each camming memberfurther includes first and second cam wedges that are laterally andlongitudinally spaced apart from each other and define a plurality ofdrive angles with respect to the base. In particular, each cam wedgedefines a first set of drive angles that may be in the range of about15° to about 55° and a second set of drive angles that may be in therange of about 5° to about 35°. In another embodiment, each cam wedgedefines a first set of drive angles that may be in the range of about25° to about 45° and a second set of drive angles that may be in therange of about 10° to about 30°. In a further embodiment, each cam wedgedefines a first set of drive angles that may be in the range of about30° to about 40° and a second set of drive angles that may be in therange of about 10° to about 30°.

In yet another embodiment of the present disclosure, each of thedescribed actuation sleds may be included at a distal end of a cam baror actuation member in a surgical stapling apparatus.

In a further embodiment of the present disclosure, the staple driveassembly may include at least one proximal staple pusher, at least onemiddle staple pusher and at least one distal staple pusher. Proximalstaple pusher is disposed at the proximal end of the staple cartridgeand is adapted to eject the outermost, most proximal staple. Distalstaple pusher is positioned on the distal end of staple cartridge and isconfigured to eject the outermost, most distal staples. Each staplepusher has first and second cam members. In turn, each cam member has atleast one engagement surface. Additionally, the proximal staple pusherhas a single pusher plate, the middle staple pusher has at least threepusher plates, and the distal staple pusher has at least four pusherplates.

As will be appreciated from the disclosure, controlled driving of thestaple pushers can be maximized by providing cam wedges which are offsetboth laterally and longitudinally from each other with each drivesurface having a first drive angle which is less than the second driveangle.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the presently disclosed staple drive assembly aredescribed herein with reference to the drawings, wherein:

FIG. 1 is a perspective view of a staple drive assembly showing anactuation sled and a staple pusher in accordance with an embodiment ofthe present disclosure;

FIG. 2 is a perspective view of an endoscopic surgical staplingapparatus;

FIG. 3 is an exploded perspective view of a staple cartridge, staples,staple pushers and an actuation sled;

FIG. 4 is a top plan view of the staple cartridge of FIG. 4 with theactuation sled in an initial position;

FIG. 5 is a side cross-sectional view of a proximal portion of thestaple cartridge taken along section line 5-5 of FIG. 4;

FIG. 6 is a front perspective view of the staple pusher of FIG. 1;

FIG. 7 is a rear perspective view of the staple pusher of FIG. 1;

FIG. 8 is a top plan view of the staple pusher of FIG. 1;

FIG. 9 is a side cross-sectional view taken along section line 9-9 ofFIG. 8;

FIG. 10 is a side cross-sectional view taken along section line 10-10 ofFIG. 8;

FIG. 11 is a front perspective view of the actuation sled of FIG. 1;

FIG. 12 is a rear perspective view of the actuation sled of FIG. 1;

FIG. 13 is a top plan view of the actuation sled of FIG. 1;

FIG. 14 is a side cross-sectional view taken along section line 14-14 ofFIG. 13;

FIG. 15 is a side cross-sectional view taken along section line 15-15 ofFIG. 13;

FIG. 16 is a side cross-sectional view of the staple drive assembly ofFIG. 1 showing the initial engagement between the cam members of thestaple pusher of FIG. 6 and the cam wedges of the actuation sled as theactuation sled moves in the direction of arrow A;

FIG. 17 is a side cross-sectional view of the staple drive assembly ofFIG. 1 showing the continued engagement between the cam members of thestaple pusher of FIG. 6 and the cam wedges of the actuation sled as theactuation sled continues to move in the direction of arrow A;

FIG. 18 is a top plan view taken along section line 18-18 of the stapledrive assembly of FIG. 17;

FIG. 19 is a front perspective view of an actuation sled according toanother embodiment of the present disclosure;

FIG. 20 is a rear perspective view of the actuation sled of FIG. 19;

FIG. 21 is a top plan view of the actuation sled of FIG. 19;

FIG. 22 is a side cross-sectional view of the actuation sled of FIG. 19taken along section line 21-21 of FIG. 21;

FIG. 23 is a side cross-sectional view of the actuation sled of FIG. 19taken along section line 23-23 of FIG. 21;

FIG. 24 is a side cross-sectional view of another embodiment of a stapledrive assembly including the actuation sled of FIG. 19 showing theinitial engagement between the cam members of the staple pusher of FIG.6 and the cam wedges of the actuation sled as the actuation sled movesin the direction of arrow A;

FIG. 25 is a side cross-sectional view of the staple drive assembly ofFIG. 24 showing the continued engagement between the cam members of thestaple pusher of FIG. 6 and the cam wedges of the actuation sled as theactuation sled continues to move in the direction of arrow A;

FIG. 26 is a rear perspective view of an alternate embodiment of astaple pusher in accordance with the present disclosure;

FIG. 27 is a top plan view of the staple pusher of FIG. 26;

FIG. 28 is a rear perspective view of another embodiment of a staplepusher in accordance with the present disclosure;

FIG. 29 is a top plan view of the staple pusher of FIG. 28;

FIG. 30 is a front perspective view of an actuation sled according toanother embodiment of the present disclosure;

FIG. 31 is a rear perspective view of the actuation sled of FIG. 30;

FIG. 32 is a top plan view of the actuation sled of FIG. 30;

FIG. 33 is a side cross-sectional view taken along section line 33-33 ofFIG. 32;

FIG. 34 is a side cross-sectional view taken along section line 34-34 ofFIG. 32;

FIG. 35 is a side cross-sectional view of another embodiment of a stapledrive assembly including the actuation sled of FIG. 30 showing theinitial engagement between the cam members of the staple pusher of FIG.6 and the cam wedges of the actuation sled as the actuation sled movesin the direction of arrow A;

FIG. 36 is a side cross-sectional view of the staple drive assembly ofFIG. 35 showing the continued engagement between the cam members of thestaple pusher of FIG. 6 and the cam wedges of the actuation sled as theactuation sled continues to move in the direction of arrow A;

FIG. 37 is a front perspective view of an actuation sled according toanother embodiment of the present disclosure;

FIG. 38 is a rear perspective view of the actuation sled of FIG. 37;

FIG. 39 is a top plan view of the actuation sled of FIG. 37;

FIG. 40 is a side cross-sectional view of the actuation sled of FIG. 39taken along section lines 40-40 of FIG. 39;

FIG. 41 is a side cross-sectional view of the actuation sled of FIG. 39taken along section line 41-41 of FIG. 39;

FIG. 42A is bottom perspective view of a pusher member according to anembodiment of the present disclosure;

FIG. 42B is side perspective view of the pusher member of FIG. 42A;

FIG. 43 is a side cross-sectional view of another embodiment of a stapledrive assembly including the actuation sled of FIG. 37 showing theinitial engagement between the cam members of the staple pusher of FIG.42A and the cam wedges of the actuation sled as the actuation sled movesin the direction of arrow A;

FIG. 44 is a side cross-sectional view of the staple drive assembly ofFIG. 43 showing the continued engagement between the cam members of thestaple pusher of FIG. 42A and the cam wedges of the actuation sled asthe actuation sled continues to move in the direction of arrow A;

FIG. 45 is a front perspective view of an actuation sled according toanother embodiment of the present disclosure;

FIG. 46 is a rear perspective view of the actuation sled of FIG. 45;

FIG. 47 is a top perspective view of the actuation sled of FIG. 45;

FIG. 48 is a side cross-sectional view of the actuation sled of FIG. 47taken along section lines 48-48 of FIG. 47;

FIG. 49 is a side cross-sectional view of the actuation sled of FIG. 47taken along section lines 49-49 of FIG. 47;

FIG. 50 is a side cross-sectional view of another embodiment of a stapledrive assembly including the actuation sled of FIG. 45 showing theinitial engagement between the cam members of the staple pusher of FIG.6 and the cam wedges of the actuation sled as the actuation sled movesin the direction of arrow A;

FIG. 51 is a side cross-sectional view of the staple drive assembly ofFIG. 50 showing the continued engagement between the cam members of thestaple pusher of FIG. 6 and the cam wedges of the actuation sled as theactuation sled continues to move in the direction of arrow A;

FIG. 52 is a side cross-sectional view of an end portion of an actuationmember according to an embodiment of the present disclosure;

FIG. 53 is a side cross-sectional view of an end portion of an actuationmember according to an alternate embodiment of the present disclosure;

FIG. 54 is a side cross-sectional view of an end portion of an actuationmember according to another embodiment of the present disclosure;

FIG. 55 is a side cross-sectional view of an end portion of an actuationmember according to a further embodiment of the present disclosure;

FIG. 56 is a side cross-sectional view of an end portion of an actuationmember according to another embodiment of the present disclosure;

FIG. 57 is a perspective view of a staple cartridge according to anembodiment of the present disclosure;

FIG. 57 a is a side perspective view of staples and a staple pusher;

FIG. 58 is a top perspective view of a double staple pusher according toan embodiment of the present disclosure;

FIG. 59 is a side perspective view of the double staple pusher of FIG.58;

FIG. 60 is a top plan view of the double staple pusher of FIG. 58;

FIG. 61 is a side cross-sectional view taken along section line 61-61 ofFIG. 60;

FIG. 62 is a top perspective view of a quadruple staple pusher accordingto an embodiment of the present disclosure;

FIG. 63 is a rear perspective view of the quadruple staple pusher ofFIG. 62;

FIG. 64 is a bottom perspective view of the quadruple staple pusher ofFIG. 62;

FIG. 65 is a top plan view of the quadruple staple pusher of FIG. 62;

FIG. 66 is a side cross-sectional view taken along section line 66-66 ofFIG. 65;

FIG. 67 is a perspective view of a staple cartridge according to anembodiment of the present disclosure;

FIG. 68 is a top perspective view of a single staple pusher according toan embodiment of the present disclosure;

FIG. 69 is a side perspective view of the single staple pusher of FIG.68;

FIG. 70 is a bottom perspective view of the single staple pusher of FIG.68;

FIG. 71 is a top plan view of the single staple pusher of FIG. 71; and

FIG. 72 is a side cross-sectional view of the single staple pusher takenalong section lines 72-72 of FIG. 71.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the presently disclosed staple drive assembly will now bedescribed in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views. As used herein, the term “distal” refers to thatportion of the instrument, or component thereof which is further fromthe user while the term “proximal” refers to that portion of theinstrument or component thereof which is closer to the user.

A staple drive assembly 100, in accordance with one embodiment of thepresent disclosure, is illustrated in FIG. 1. Staple drive assembly 100includes an actuation sled 110 and at least one staple pusher 160.Actuation sled 110 includes a base 112, a first camming member 120, asecond camming member 140, and a guide member 150. First and secondcamming members 120, 140 include respective first or leading cam wedges122, 142 and respective second or trailing cam wedges 124, 144. In oneembodiment, staple drive assembly 100 is adapted for use in a surgicalstapler having at least two linear rows of staples such as an endoscopicor laparoscopic stapler.

An example of a surgical stapler having linear rows of staples isdisclosed in U.S. Pat. No. 6,669,073 to Milliman et al. currently ownedand assigned to United States Surgical, the entire contents of which areincorporated herein by reference. As illustrated in FIG. 2, the surgicalstapler is shown generally as 10. Surgical stapler 10 includes a triggerassembly 30, a body portion 12, a staple cartridge 40, and an anvilassembly 70. Trigger assembly 30 includes a pivotal trigger 32. Pivotalmovement of trigger 32 during an actuation sequence of trigger 32translates pivotal movement of trigger 32 into linear movement of adrive mechanism (not shown). The drive mechanism is operatively coupledto an actuation sled in staple cartridge 40 to translate linear movementof the drive mechanism to linear movement of the actuation sled. Stapler10 is movable such that a portion of body tissue (not shown) may bepositioned between anvil assembly 70 and staple cartridge 40. Actuationof stapler 10 moves anvil assembly 70 towards staple cartridge 40thereby grasping or retaining the portion of body tissue therebetween.In addition, once the portion of body tissue is grasped between anvilassembly 70 and staple cartridge 40, continued actuation of stapler 10discharges staples 50 (FIG. 3) through the portion of body tissue andagainst anvil assembly 70 to form completed staples 50. The presentlydisclosed staple drive assembly 100 may be incorporated into staplecartridge 40 of surgical stapler 10 disclosed in U.S. Pat. No.6,669,073. Alternately, staple drive assembly 100 may be incorporatedinto other known stapling devices including open-type surgical staplingdevices, such as the open surgical staplers shown and described U.S.Pat. Nos. 4,955,959; 4,978,049; 5,395,034; 5,630,541; 5,662,258;6,131,789 and D278,081 and other endoscopic or laparoscopic surgicalstapling devices, such as the endoscopic staplers shown and described inpublished U.S. Patent Applications 2004/0232195; 2004/0232197 and2004/0232199. While the present disclosure describes embodimentsinvolving an actuation sled, it also will be appreciated that the designcharacteristics and function of the sled camming members may beincorporated directly into cam bars or firing wedges, which in turn areconnected to the firing mechanism of the surgical stapling instrument.

FIG. 3 illustrates a staple cartridge 40′ including the staple driveassembly shown in FIG. 1. Staple cartridge 40′ includes a plurality offasteners or staples 50 and a corresponding number of staple pockets orretention slots 60. A tissue contacting surface 44 is defined by a topsurface of staple cartridge 40′. A guide channel 42 extendssubstantially the length of staple cartridge 40′ and is adapted forslidably receiving guide member 150 of actuation sled 110 as shown inFIG. 4. In FIG. 4, sled 110 is shown positioned at the proximal end ofcartridge 40′ with guide member 150 disposed in guide channel 42. Guidechannel 42 cooperates with guide member 150 for aligning and positioningactuation sled 110 in staple cartridge 40′ as it translateslongitudinally from a proximal end to a distal end of staple cartridge40′. Guide channel 42 may also facilitate passage of a knife blade (notshown) through cartridge 40′, such as by mounting a knife blade to guidemember 150.

In FIG. 5, a cross-sectional view taken along line 5-5 of FIG. 4,actuation sled 110 is shown disposed in the proximal end of staplecartridge 40′ in a first or ready position. In the ready position,actuation sled 110 is capable of translating distally through staplecartridge 40′ (i.e. in the direction indicated by arrow A) andsequentially engaging staple pushers 160 (FIG. 3) as discussed in detailhereinbelow. Actuation sled 110 is translatable along a longitudinalaxis of staple cartridge 40′ from its ready position to a second or endposition located in a distal portion of staple cartridge 40′.

Turning now to FIGS. 6-10, several views of one embodiment of staplepusher 160 are illustrated. Each staple pusher 160 includes a first cammember 162, a second cam member 164, and at least one prong or pusherplate 166. In one embodiment, each staple pusher 160 includes threepusher plates 166 that are laterally and longitudinally spaced apartfrom each other. Generally, first and second cam members 162, 164 andpusher plates 166 lie in a plane parallel to a longitudinal axis ofstaple cartridge 40′. As illustrated in FIGS. 6 and 7, each pusher plate166 includes a leading edge 166 a and a trailing edge 166 b. In oneembodiment, pusher plates 166 may be longitudinally spaced apart orstaggered such that the longitudinal spacing between leading edges 166 aof adjacent pusher plates 166 is about two-thirds the length ofretention slot 60 or about two-thirds the length of an adjacent pusherplate 166. Further still, each pusher plate 166 includes a top surface166 c that is adapted for releasably engaging a backspan 52 of a staple50 (see FIG. 1). Each retention slot 60 of staple cartridge 40′ isconfigured for releasably receiving a staple 50 and a pusher plate 166(see FIG. 3). Additionally, each staple includes two legs 54.

As previously discussed, staple pusher 160 includes prongs or pusherplates 166 that are laterally and longitudinally spaced apart as well asfirst and second cam members 162, 164 interposed between adjacent pusherplates 166. More specifically, as discussed hereinabove, in oneembodiment of the present disclosure, each staple pusher 160 includes aplurality of pusher plates 166 that are substantially parallel to alongitudinal axis of staple cartridge 40′ and parallel to a centerlineCL of each staple pusher 160 (FIG. 8). Additionally, first and secondcam members 162, 164 are also substantially parallel to centerline CL(FIG. 8). Staple pusher 160, as viewed from left to right in FIG. 8(i.e. distal to proximal), includes an inboard pusher plate 166 that ismost distal along centerline CL. A middle pusher plate 166 is laterallyspaced apart from inboard pusher plate 166 and is axially offset in theproximal direction from inboard pusher plate 166. An outboard pusherplate 166 is laterally spaced apart from middle pusher plate 166 and isaxially offset in the proximal direction from middle pusher plate 166.Further still, first cam member 162 is disposed between inboard pusherplate 166 and middle pusher plate 166 while second cam member 164 isdisposed between middle pusher plate 166 and outboard pusher plate 166.Configured thusly, staple pusher 160 has an arrangement where pusherplates 166 are longitudinally staggered from a distal portion of staplepusher 160 to a proximal portion of staple pusher 160 as seen in FIG. 8.

First and second cam members 162, 164 include respective first andsecond cam surfaces 162 a, 162 b and 164 a, 164 b (FIGS. 9 and 10). Atthe intersection of first and second cam surfaces 162 a, 162 b and 164a, 164 b are respective transition points 162 c, 164 c. A plane T (FIG.10) extending through transition points 162 c, 164 c is parallel torespective tops 163, 165 of cam members 162, 164. In one embodiment,first cam surfaces 162 a, 164 a define a first engagement or receivingangle with respect to tops 163, 165 of respective first and second cammembers 162, 164. Second cam surfaces 162 b, 164 b define a secondengagement or receiving angle with respect to plane T. First and secondreceiving angles are complementary to respective first and second driveangles of camming members 120, 140 of actuation sled 110 as discussed indetail hereinbelow. In one embodiment, the first receiving angles may bein a range of about 15° to about 55° while the second receiving anglesmay be in a range of about 5° to about 35°. In another embodiment, thefirst receiving angles may be in a range of about 25° to about 45° whilethe second receiving angles may be in a range of about 10° to about 30°.In a further embodiment, first receiving angles may be in a range ofabout 30° to about 40° while second receiving angles may be in a rangeof about 15° to about 25°.

Alternate embodiments of the presently disclosed staple pusher areillustrated in FIGS. 26-29 and discussed in detail hereinbelow.Initially referring to FIGS. 26-27, staple pusher 260 is illustrated andincludes the same or substantially similar components to staple pusher160. Each staple pusher 260 includes a first cam member 262, a secondcam member 264, and a single prong or pusher plate 266. Generally, firstand second cam members 262, 264 and pusher plates 266 lie in a planeparallel to a longitudinal axis of staple cartridge 40′. As illustratedin FIGS. 26 and 27, each pusher plate 266 includes a leading edge 266 aand a trailing edge 266 b. Further still, each pusher plate 266 includesa top surface 266 c that is adapted for releasably engaging a backspan52 of a staple 50 (see FIG. 1). Each retention slot 60 of staplecartridge 40′ is configured for releasably receiving a staple 50 and apusher plate 266 (see FIG. 3).

Staple pusher 260 includes a prong or a pusher plate 266 that separatesfirst and second cam members 262, 264. More specifically, each staplepusher 260 includes a single pusher plate 266 that is substantiallyparallel to a longitudinal axis of staple cartridge 40′ and parallel toa centerline CL of each staple pusher 260 (FIG. 27). Additionally, firstand second cam members 262, 264 are also substantially parallel tocenterline CL (FIG. 27).

First and second cam members 262, 264 include respective first andsecond cam surfaces 262 a, 262 b and 264 a, 264 b (FIG. 26). At theintersection of first and second cam surfaces 262 a, 262 b and 264 a,264 b are respective transition points 262 c, 264 c. A plane T (FIG. 26)extending through transition points 262 c, 264 c is parallel torespective tops 263, 265. In one embodiment, first cam surfaces 262 a,264 a define a first engagement or receiving angle with respect to tops263, 265 of respective first and second cam members 262, 264. Second camsurfaces 262 b, 264 b define a second engagement or receiving angle withrespect to plane T. First and second receiving angles are complementaryto respective first and second drive angles of camming members 120, 140as discussed in detail hereinbelow. In one embodiment, the firstreceiving angles may be in a range of about 15° to about 55° while thesecond receiving angles may be in a range of about 5° to about 35°. Inanother embodiment, the first receiving angles may be in a range ofabout 25° to about 45° while the second receiving angles may be in arange of about 10° to about 30°. In a further embodiment, firstreceiving angles may be in a range of about 30° to about 40° whilesecond receiving angles may be in a range of about 15° to about 25°.

Referring now to FIGS. 28 and 29, another embodiment of the staplepusher of the present disclosure is shown and referenced as 360. Eachstaple pusher 360 includes a first cam member 362, a second cam member364, and two prongs or pusher plates 366 that are laterally andlongitudinally spaced apart from each other. Generally, first and secondcam members 362, 364 and pusher plates 366 lie in a plane parallel to alongitudinal axis of staple cartridge 40′. As illustrated in FIGS. 28and 29, each pusher plate 366 includes a leading edge 366 a and atrailing edge 366 b. Pusher plates 366 may be longitudinally spacedapart or staggered such that the longitudinal spacing between leadingedges 366 a of adjacent pusher plates 366 is about two-thirds the lengthof retention slot 60 or about two-thirds the length of pusher plate 366.Further still, each pusher plate 366 includes a top surface 366 c thatis adapted for releasably engaging a backspan 52 of a staple 50 (seeFIG. 1). Each retention slot 60 of staple cartridge 40′ is configuredfor releasably receiving a staple 50 and a pusher plate 366 (see FIG.3).

First and second cam members 362, 364 include respective first andsecond cam surfaces 362 a, 362 b and 364 a, 364 b (FIGS. 28 and 29). Atthe intersection of first and second cam surfaces 362 a, 362 b and 364a, 364 b are respective transition points 362 c, 364 c. A plane T (FIG.28) extending through transition points 362 c, 364 c is parallel torespective tops 363, 365. In one embodiment, first cam surfaces 362 a,364 a define a first engagement or receiving angle with respect to tops363, 365 of respective first and second cam members 362, 364. Second camsurfaces 362 b, 364 b define a second engagement or receiving angle withrespect to plane T. First and second receiving angles are complementaryto respective first and second drive angles of camming members 120, 140as discussed in detail hereinbelow. In one embodiment, the firstreceiving angles may be in a range of about 15° to about 55° while thesecond receiving angles may be in a range of about 5° to about 35°. Inanother embodiment, the first receiving angles may be in a range ofabout 25° to about 45° while the second receiving angles may be in arange of about 10° to about 30°. In a further embodiment, firstreceiving angles may be in a range of about 30° to about 40° whilesecond receiving angles may be in a range of about 15° to about 25°.

With reference to FIGS. 11-15, several views of one embodiment ofactuation sled 110 are shown. First and second camming members 120, 140each include a first or leading cam wedge 122, 142, respectively, thatis laterally and longitudinally spaced apart from a second or trailingcam wedge 124, 144, respectively. The lateral and longitudinal offsetdistances of each pair of camming wedges substantially corresponds tothe lateral and longitudinal offset distances between corresponding cammembers 162, 164. First cam wedges 122, 142 are laterally andlongitudinally spaced from second cam wedges 124, 144, respectively, bya substantially identical amount such that first and second cammingmembers 120, 140 are symmetrical about a central longitudinal axis ofactuation sled 110. Leading cam wedges 122, 142 include respective firstand second drive faces 122 a, 122 b, 142 a, and 142 b. First drive faces122 a, 142 a form first drive angles on camming members 120, 140 withrespect to base 112 of actuation sled 110. At the intersection of firstand second drive faces 122 a, 142 a and 122 b, 142 b are respectivetransition points 123, 143. A plane X extending through transitionpoints 123, 143 is substantially parallel to base 112. Second drivefaces 122 b, 142 b form respective second drive angles on cammingmembers 120, 140 with respect to plane X. Plane X is also substantiallyparallel to tissue contacting surface 44 of staple cartridge 40′.

Similarly, trailing cam wedges 124, 144 include respective first andsecond drive faces 124 a, 124 b, 144 a, and 144 b. First drive faces 124a, 144 a form first drive angles on camming members 120, 140 withrespect to base 112 (FIG. 5) of actuation sled 110. At the intersectionof first and second drive faces 124 a, 124 b and 144 a, 144 b arerespective transition points 125, 145. Plane X extends throughtransition points 125, 145 and is substantially parallel to base 112.Second drive faces 124 b, 144 b form respective second drive angles oncamming members 120, 140 with respect to plane X. In one embodiment,first drive angles may be in a range of about 15° to about 55° whilesecond drive angles may be in a range of about 5° to about 35°. Inanother embodiment, first drive angles may be in a range of about 25° toabout 45° while second drive angles may be in a range of about 10° toabout 30°. In a further embodiment, first drive angles may be in a rangeof about 30° to about 40° while second drive angles may be in a range ofabout 15° to about 25°.

Interaction between actuation sled 110 and staple pusher 160 of stapledrive assembly 100 is shown in FIGS. 16-18 and discussed in detailhereinafter. Initially, as illustrated in FIG. 16, actuation sled 110translates distally through staple cartridge 40′ in the directionindicated by arrow A (see also FIG. 5) causing first drive face 122 a toslidably engage first cam surface 162 a and urge staple pusher 160 fromits first or rest position in a generally vertical direction asindicated by arrow B. Because the lateral and longitudinal offsetdistances of wedges 122, 124 correspond to the lateral and longitudinaloffset distances between cam wedges 162, 164, first drive face 124 asubstantially simultaneously slidably engages first cam surface 164 athereby urging staple pusher 160 in a generally vertical direction asindicated by arrow B. Since cam surfaces 162 a and 164 a arelongitudinally offset, staple pusher 160 is driven in a controlled andbalanced manner and any tendency of staple pusher 160 to tilt or rotatecounterclockwise (as viewed in FIGS. 16-17) is minimized as staplepusher 160 is driven through retainer slot 60. First drive faces 122 a,124 a and respective first cam surfaces 162 a, 164 a have complementaryangles that maximize translation of longitudinal motion of actuationsled 110 to vertical motion of staple pusher 160.

Referring now to FIG. 17, continued distal movement of actuation sled110 further urges staple pusher 160 generally vertically to anintermediate position, such that second drive faces 122 b, 124 bslidably engage respective second cam surfaces 162 b, 164 b while firstdrive faces 122 a, 124 a substantially simultaneously disengage fromrespective first cam surfaces 162 a, 164 a. Similarly, second drivefaces 122 b, 124 b and respective second cam surfaces 162 b, 164 b havecomplementary angles to maximize translation of longitudinal motion ofactuation sled 110 to vertical motion of staple pusher 160. Thecorresponding lateral and longitudinal offset of second drive faces 122b, 124 b and respective second cam surfaces 162 b, 164 b continue tocontrol the advancement of staple pusher 160 so as to minimize anytendency of staple pusher 160 to tilt or rotate in a counterclockwisedirection as viewed in FIGS. 16-17. Continuing distal movement ofactuation sled 110 continues to urge staple pusher 160 vertically to itssecond or end position immediately prior to the disengagement betweensecond drive faces 122 b, 124 b and respective second cam surfaces 162b, 164 b.

Since the interaction between second camming member 140 and staplepusher 160 is substantially identical to the intersection of firstcamming member 120 and pusher 160, the intersection of second cammingmember 140 and staple pusher 160 will not be described in detail herein.

Longitudinal motion of actuation sled 110 in the direction indicated byarrow A results in first and second camming members 120, 140 slidablyengaging staple pushers 160 as shown in FIGS. 16-18. Sliding engagementbetween leading cam wedges 122, 142 and first cam members 162 incooperation with the substantially simultaneous engagement betweentrailing cam wedges 124, 144 and second cam members 164 improve thelongitudinal stability of the staple pushers 160 during vertical motionas follows. Leading cam wedges 122, 142 are longitudinally spaced apartfrom trailing cam wedges 124, 144 by a predetermined amount. Sincerespective first and second cam members 162, 164 are longitudinallyspaced apart by a comparable, but complementary amount, longitudinalmovement of actuation sled 110 results in the substantiallysimultaneous, but offset engagement of leading cam wedges 122, 124 andtrailing cam wedges 124, 144 with respective first and second cammembers 162, 164 thereby transferring the longitudinal movement ofactuation sled 110 to vertical movement of staple pusher 160 atlongitudinally spaced apart impact points. By transferring longitudinalmovement of actuation sled 110 to each staple pusher 160 at twolongitudinally spaced apart impact points, substantially balancedvertical movement of each staple pusher 160 is achieved. Since there istwo point contact between first and second camming members 120, 140 andrespective first and second cam members 162, 164 throughout the verticaltravel of each staple pusher 160, pivoting or tilting of each staplepusher 160 is minimized due to the two-point contact arrangement.Minimizing pivoting or tilting of each staple pusher 160 during verticaltravel further minimizes pivoting or tilting of each staple 50 as eachstaple 50 is driven vertically in its respective retention slot 60. Thisprovides more precise contact of a staple with an anvil pocket (notshown) and thus, improved staple formation.

In addition, the lateral offset between cam wedges 122, 124 of firstcamming member 120 and cam wedges 142, 144 of second camming member 140inhibits “rocking” of staple pusher 160. “Rocking” of staple pushers mayoccur when the lifting force applied to the staple pusher by theactuation sled is not balanced creating a tendency for the staple pusherto “rock” in a direction that is transverse to the movement of theactuation sled. This “rocking” movement may cause misalignment of thestaple during a firing sequence resulting in non-uniform stapleformation. In extreme circumstances, “rocking” may cause a “front jump”staple formation wherein the rear leg of a staple exits the staplecartridge at an angle and enters the anvil pocket at the same locationas the front leg of the same staple. By providing actuation sled 110with laterally offset cam wedges, actuation sled 110 contacts staplepusher 160 at two laterally spaced contact points substantiallysimultaneously, thereby imparting a lifting force to staple pusher 160that is substantially balanced between first and second cam members 162,164. Therefore, engagement of actuation sled 110 with staple pusher 160results in substantially even vertical motion of staple pusher 160 andinhibits “rocking” of staple pusher 160 and inhibits front jump stapleformation.

Further still, as previously discussed, each cam wedge (122, 124, 142,144) defines a plurality of receiving angles that are complementary todrive angles defined by cam members 162, 164. When the first drive angleis greater than the second drive angle, single point contact between thestaple pusher and the cam wedge may occur. Instability of the staplepusher due to such single point contact can also result in tilting orrotation of the staple pusher during firing. Such instability is mostlikely to occur as the staple pusher transitions from contacting onedrive surface to the other drive surface. As described above, unbalancedvertical movement of staple pusher 160 can cause staple pusher 160 totravel vertically at an angle such that top surfaces 166 c (FIG. 1) ofstaple pusher 160 are not substantially parallel to tissue contactingsurface 44 or backspan 52 of staple 50 (FIG. 3). This may lead toimproperly formed staples, misalignment of the staples with the anvilpockets, or misalignment of the staples with the retention slots. Byproviding different angles on each cam wedge, an angular differential isdefined wherein the angular differential minimized “rotation” of staplepusher 160.

Interaction between actuation sled 110 and staple pushers 260, 360 issubstantially similar to the interaction described hereinabove betweenactuation sled 110 and staple pusher 160 and will not be discussed indetail. It is sufficient to note that staple pushers 260, 360 may befreely substituted for staple pusher 160.

Referring now to FIGS. 19-25, another embodiment of the presentlydisclosed staple drive assembly 200 is illustrated (FIGS. 24-25). Stapledrive assembly 200 includes an actuation sled 210 (FIGS. 19-23) and atleast one staple pusher 160 (FIGS. 6-10). Actuation sled 210 is adaptedand configured for use in staple cartridge 40′ as an alternative foractuation sled 110. As seen in FIGS. 19-23, actuation sled 210 includesa first camming member 220, a second camming member 240, and a guidemember 250. First and second camming members 220, 240 include respectivefirst or leading cam wedges 222, 242 and respective second or trailingcam wedges 224, 244.

Similar to actuation sled 110, leading cam wedges 222, 242 of actuationsled 210 include first drive faces 222 a, 242 a and second drive faces222 b, 242 b. Interposed between first drive faces 222 a, 242 a andsecond drive faces 222 b, 242 b are respective first and secondtransition points 223, 243. First drive faces 222 a, 242 a extendproximally from a distal point 214 both longitudinally and verticallythereby forming a first drive angle with respect to base 212. Trailingcam wedges 224, 244 are longitudinally spaced apart from leading camwedges 222, 242 by a predetermined distance. First drive faces 224 a,244 a of trailing cam wedges 224, 244 extend both longitudinally andvertically in a proximal direction from respective origin points 214 a,214 b to form the first drive angle with respect to base 212. A plane X′extending through transition points 223, 243 (FIG. 23) of leading camwedges 222, 242 is parallel to base 212. Second drive faces 222 b, 242 bform respective second drive angles with respect to plane X′.Additionally, plane X′ extends through transition points 225, 245 (FIG.23) of trailing cam wedges 224, 244 and is substantially parallel tobase 212. Plane X′ is also substantially parallel to tissue contactingsurface 44 of staple cartridge 40′. Second drive faces 224 b, 244 b formrespective second drive angles with respect to plane X′. In oneembodiment, first drive angles may be in a range of about 5° to about35° while second drive angles may be in a range of about 20° to about55°. In another embodiment, first drive angles may be in a range ofabout 10° to about 30° while second drive angles may be in a range ofabout 25° to about 45°. In a further embodiment, first drive angles maybe in a range of about 15° to about 25° while the second drive anglesmay be in a range of about 30° to about 40°. By providing actuation sled210 with first drive faces 222 a, 242 a having a flatter initialengaging surface having a lower angle relative to a plane parallel tobase 212, interaction between actuation sled 210 and each staple pusher160 is more controllable. As actuation sled 210 translates throughstaple cartridge 40′ and interacts with each staple pusher as discussedabove, actuation sled 210 gradually and controllably urges each staplepusher 160 vertically as actuation sled 210 translates through staplecartridge 40′.

In staple drive assembly 200, the interaction between actuation sled 210and staple pusher 160 is illustrated in FIGS. 24-25 and discussed indetail hereinafter. As actuation sled 210 moves distally through staplecartridge 40′ (see FIG. 5) in a generally horizontal direction asindicated by arrow A, first drive faces 222 a, 224 a contact respectivesecond cam surfaces 162 b, 164 b and urge staple pusher 160 in agenerally vertical direction as indicated by arrow B from its first orrest position. Since the first drive angle is defined by first drivefaces 222 a, 224 a and is complementary to the second receiving angledefined by second cam surfaces 162 b, 164 b, horizontal movement ofactuation sled 210 in direction A causes vertical movement of staplepusher 160 in direction B.

As actuation sled 210 continues to move in the direction of arrow A,second drive faces 222 b, 224 b engage respective first cam surfaces 162a, 164 a and first drive faces 222 a, 224 a remain engaged with theirrespective second cam surfaces 162 b, 164 b, thereby providingadditionally longitudinal and vertical stability of staple pusher 160.After actuation sled 210 moves a predetermined distance in the directionof arrow A, first drive faces 222 a, 224 a disengage from theirrespective second cam surfaces 162 b, 164 b while second drive faces 222b, 224 b remain engaged with their respective first cam surfaces 162 a,164 a. The second drive angle defined by second drive faces 222 b, 224 bis complementary to the first receiving angle defined by first camsurfaces 162 a, 164 a further urging staple pusher 160 in the directionof arrow B through an intermediate position. Continuing distal movementof actuation sled 210 continues to urge staple pusher 160 vertically toits second or end position immediately prior to the disengagementbetween second drive faces 222 b, 224 b and respective second camsurfaces 162 a, 164 a. A cam wedge having a first drive angle which isless than the second drive angle creates multiple contact points betweenthe cam wedge and the staple pusher as the staple pusher transitionsfrom contacting the first drive surface to contacting the second drivesurface, thereby further enhancing the stability of the staple pusherduring firing. In addition, providing a first drive angle less than thesecond drive angle minimizes misalignment since there is additionalsupport for the staple pusher during its vertical movement.

Since the interaction between second camming member 240 and staplepusher 160 is substantially identical to the interaction between firstcamming member 220 and staple pusher 160, the interaction between secondcamming member 240 and staple pusher 160 will not be described infurther detail herein. It is sufficient to note that staple pushers 260,360 may be freely substituted for staple pusher 160.

The sliding engagement between leading cam wedges 222, 242 and first cammembers 162 in cooperation with the substantially simultaneousengagement between trailing cam wedges 224, 244 and second cam members164 is substantially similar to that discussed hereinabove for stapledrive assembly 100 and improves the longitudinal stability of the staplepushers 160 during vertical motion.

Interaction between actuation sled 210 and staple pushers 260, 360 issubstantially similar to the interaction described hereinabove betweenactuation sled 210 and staple pusher 160 and will not be discussed indetail.

Referring now to FIGS. 30-36, another embodiment of the presentlydisclosed staple drive assembly 300 is illustrated (FIGS. 35-36). Stapledrive assembly 300 includes an actuation sled 310 (FIG. 30-34) and atleast one staple pusher 160 (FIGS. 6-10). Actuation sled 310 is adaptedand configured for use in staple cartridge 40′ as an alternative foractuation sled 110 or actuation sled 210.

As shown in FIGS. 30-34, actuation sled 310 includes a first cammingmember 320, a second camming member 340, and a guide member 350. Firstand second camming members 320, 340 include respective first or leadingcam wedges 322, 342 and respective second or trailing cam wedges 324,344.

Similar to actuation sleds 110 and 210, trailing cam wedges 324, 344 arelaterally and longitudinally spaced apart from leading cam wedges 322,342 by a predetermined distance. Leading cam wedges 322, 342 includeleading drive faces 322 a, 342 a while trailing cam wedges 324, 344include trailing drive faces 324 a, 344 a. Drive faces 324 a, 344 a oftrailing cam wedges 324, 344 extend both longitudinally and verticallyin a proximal direction from respective origin points 314 a, 314 a.Drive faces 322 a, 342 a of leading cam wedges also extend bothlongitudinally and vertically in a proximal direction from respectiveorigin points 314 a, 316 b. Drive faces 322 a, 342 a, 324 a, 344 a eachform a drive angle with respect to base 312 wherein the drive angle issubstantially identical for drive faces 322 a, 342 a, 324 a, 344 a. Inone embodiment, the drive angle may be in a range of about 15° to about25°. In another embodiment, the drive angle may be in a range of about10° to about 30°. In a further embodiment, the drive angle may be in arange of about 5° to about 35°.

In staple drive assembly 300, the interaction between actuation sled 310and staple pusher 160 is illustrated in FIGS. 35-36 and discussed indetail hereinafter. As actuation sled 310 moves distally through staplecartridge 40′ (see FIG. 5) in a generally horizontal direction asindicated by arrow A, drive faces 322 a, 324 a engage cam surfaces 162,164 of staple pusher 160 and urge staple pusher 160 in a generallyvertical direction as indicated by arrow B from its first or restposition. As in previous embodiments, cam surfaces 162, 164 definereceiving angles that are complementary to the drive angle formed bydrive faces 322 a, 324 a. Cam surfaces 162, 164 are laterally andlongitudinally spaced apart so that the spacing of cam surfaces 162, 164corresponds to the lateral and longitudinal spaced of the cam wedgedrive faces. As actuation sled 310 moves distally through staplecartridge 40′, cam surfaces 162, 164 of staple pusher 160 maintain theirengagement with drive faces 322 a, 324 a of actuation sled 310. As willbe appreciated, the lateral and longitudinal spacing of the cam wedgesand cam surfaces provides improved stability to the staple pusher duringfiring, as described above, albeit without the varied drive angles ofthe drive surfaces.

Since the interaction between second camming member 340 and staplepusher 160 is substantially identical to the interaction between firstcamming member 320 and staple pusher 160, the interaction between secondcamming member 340 and staple pusher 160 will not be described infurther detail herein. It is sufficient to note that staple pushers 260,360 may be freely substituted for staple pusher 160.

The sliding engagement between leading cam wedges 322, 342 and first cammembers 162 in cooperation with the substantially simultaneousengagement between trailing cam wedges 324, 344 and second cam members164 is substantially similar to that discussed hereinabove for stapledrive assembly 100, 200 and improves the longitudinal stability of thestaple pushers 160 during vertical motion.

Interaction between actuation sled 310 and staple pushers 260, 360 issubstantially similar to the interaction described hereinabove betweenactuation sled 310 and staple pusher 160 and will not be discussed indetail.

Referring now to FIGS. 37-44 another embodiment of the presentlydisclosed staple drive assembly 400 is illustrated (FIGS. 43-44). Stapledrive assembly 400 includes an actuation sled 410 (FIGS. 37-41) and atleast one staple pusher 460 (FIGS. 42A-42B). Actuation sled 410 isadapted and configured for use in staple cartridge 40′ (FIG. 4).

As shown in FIGS. 42A-B, staple pusher 460 includes a first cam member462, a second cam member 464, and at least one prong or pusher plate466. In one embodiment, staple pusher 460 includes three pusher plates466 that are laterally spaced apart from each other by first and secondcam members 462, 464. Generally, first and second cam members 462, 464and pusher plates 466 lie in a plane parallel to the longitudinal axisof staple cartridge 40′. Each pusher plate 466 includes a leading edge466 a, a trailing edge 466 b, and a top surface 466 c. In oneembodiment, one pusher plate 466 may be longitudinally spaced such thatpusher plates 466 are in a staggered orientation with respect to eachother such that the two outside pusher plates are laterally aligned witheach other, but the middle pusher plate is displaced from lateralalignment with the side pusher plates. An example of a suitable staplepusher is disclosed in U.S. Pat. No. 4,978,049 to Green, currently ownedby Tyco Healthcare Group LP, the entire contents of which areincorporated herein by reference.

First and second cam members 462, 464 include respective cam surfaces462 a, 464 a (FIG. 42A). In one embodiment, cam surfaces 462 a, 464 adefine an engagement or receiving angle with respect to tops 463, 465 ofrespective first and second cam members 462, 464. The receiving angle iscomplementary to a first drive angle of camming members 420, 440 ofactuation sled 410 as discussed in detail hereinbelow. In oneembodiment, the receiving angle may be in a range of about 15° to about25°. In another embodiment, the receiving angle may be in a range ofabout 17° to about 23°. In a further embodiment, the receiving angle maybe in a range of about 19° to about 21°.

With reference to FIGS. 37-41, actuation sled 410 of staple driveassembly 400 includes first and second camming members 420, 440 eachhaving a first cam wedge 422, 442, respectively, that is laterallyspaced apart from a second cam wedge 424, 444, respectively. First camwedges 422, 442 are laterally spaced from second cam wedges 424, 444,respectively, by a substantially identical amount such that first andsecond camming members 420, 440 are substantially symmetrical about acentral longitudinal axis of actuation sled 410. Each cam wedge 422,424, 442, 444 includes a plurality of drive faces as shown in FIGS.37-38 where each of the respective drive faces are indicated byreference characters “a-d.” A plane Y extends through the intersectionbetween drive faces “a” and “b.” Plane Y is substantially parallel to abase 412 and to tissue contacting surface 44 of staple cartridge 40′(see FIG. 3). First cam wedge 422 will be discussed in detail below toillustrate the relationship between the drive faces with cam wedges 424,442, and 444 having substantially identical relationships.

First cam wedge 424 of cam member 420 includes first through fourthdrive faces 424 a, 424 b, 424 c, and 424 d as shown in FIG. 41. Firstdrive face 422 a defines a first angle with respect to base 412 whilesecond drive face 422 b defines a second drive angle with respect toplane Y. In addition, the slope of drive faces 422 c and 422 d aresubstantially identical to the slopes of drive faces 422 a and 422 brespectively. In one embodiment of actuation sled 410, the first andthird drive angles (i.e. defined by drive faces 422 a, 442 c) may be ina range of about 15° to about 25°. In another embodiment, the first andthird drive angles may be in a range of about 17° to about 23°. In afurther embodiment, the first and third drive angles may be in a rangeof about 19° to about 21°. The second drive angle (i.e. defined by drivefaces 422 b, 422 d) may be in a range of about 26° to 36°. In anotherembodiment, the second drive angle may be in a range of about 28° to34°. In a further embodiment, the second drive angle may be in a rangeof about 30° to about 32°.

Interaction between actuation sled 410 and staple pusher 460 of stapledrive assembly 400 is shown in FIGS. 43-44 and discussed in detailhereinafter. Initially, as illustrated in FIG. 43, actuation sled 410translates distally through staple cartridge 40′ in the directionindicated by arrow A causing cam wedges 422, 424 of first cam member 420to slidably engage staple pusher 460. Specifically, first drive faces422 a, 424 a substantially simultaneously slidably engage respective camsurfaces 462 a, 464 a and urge staple pusher 460 from its first or restposition in a generally vertical direction as indicated by arrow B. Inone embodiment of staple drive assembly 400, the first and third driveangles of cam wedges 422, 424, 442, and 444 are complementary to thefirst receiving angle of cam surfaces 462 a, 464 a. As actuation sled410 moves distally with drive faces 422 a, 424 a in slidable engagementwith respective cam surfaces 462 a, 464 a (i.e. engaging the first driveangle), top surfaces 466 c of pusher plates 466 engage backspan 52 ofstaple 50 and urge staple 50 in a substantially vertical direction andengages tissue in contact with tissue contacting surface 44. Asactuation sled 410 continues distal movement, cam surfaces 462 a, 464 aslidably engage respective second drive faces 422 b, 424 b continuing tourge staple 50 vertically. As illustrated in FIG. 44, continued distaltranslation of actuation sled 410 causes cam surfaces 462 a, 464 a toslidably engage drive faces 422 c, 424 c (i.e. engaging the third driveangle), thereby moving legs 54 of staple 50 into engagement with anvilassembly 70 to form completed staples 50. By providing first and thirddrive angles of respective first drive faces 422 a, 424 a, and thirddrive faces 422 c, 424 c that are complementary to the receiving anglesof cam surfaces 462 a, 464 a, the interaction between the distalmovement of actuation sled 410 and staple pusher 460 may reduce thefiring force necessary to fire staples 50. In addition to matching thedrive angles and the receiving angles, first drive faces 422 a, 424 aare spaced apart from third drive faces 422 c, 424 c by a predetermineddistance thereby further minimizing kicking of staple pusher 460 asstaple 50 engages tissue and anvil assembly 70, respectively.

Since the interaction between second camming member 440 and staplepusher 460 is substantially identical to the interaction of firstcamming member 420 and pusher 460, the interaction of second cammingmember 440 and staple pusher 460 will not be described in detail herein.

In addition, another embodiment of the staple drive assembly isillustrated in FIGS. 45-51 and referenced generally as 500 (FIGS.50-51). Staple drive assembly 500 includes actuation sled 510 (FIGS.45-49) having first and second camming members 520, 540 each having afirst cam wedge 522, 542, respectively, that is laterally spaced apartfrom a second cam wedge 524, 544, respectively. First cam wedges 522,542 are laterally spaced from second cam wedges 524, 544, respectively,by a substantially identical amount such that first and second cammingmembers 520, 540 are substantially symmetrical about a centrallongitudinal axis of actuation sled 510. Each cam wedge 522, 524, 542,544 includes a plurality of drive faces as shown in FIGS. 45-46 whereeach of the respective drive faces are indicated by reference characters“a-d.” A plane Y extends through the intersection between drive faces“a” and “b.” Plane Y is substantially parallel to a base 512 and totissue contacting surface 44 of staple cartridge 40′ (FIG. 3). Inaddition, first cam wedges 522, 542 are longitudinally spaced fromsecond cam wedges 524, 544. First cam wedge 522 will be discussed indetail below to illustrate the relationship between the drive faces withcam wedges 524, 542, and 544 having substantially identicalrelationships.

First cam wedge 522 of cam member 520 includes first through fourthdrive faces 522 a, 522 b, 522 c, and 522 d as shown in FIG. 48. Firstdrive face 522 a defines a first angle with respect to base 512 whilesecond drive face 522 b defines a second drive angle with respect toplane Y. In addition, the slope of drive faces 522 c and 522 d aresubstantially identical to the slopes of drive faces 522 a and 522 brespectively. In one embodiment of actuation sled 510, the first andthird drive angles (i.e. defined by drive faces 522 a, 542 c) may be ina range of about 15° to about 55°. In another embodiment, the first andthird drive angles may be in a range of about 25° to about 45°. In afurther embodiment, the first and third drive angles may be in a rangeof about 30° to about 40°. The second drive angle (i.e. defined by drivefaces 522 b, 522 d) may be in a range of about 5° to 35°. In anotherembodiment, the second drive angle may be in a range of about 10° to30°. In a further embodiment, the second drive angle may be in a rangeof about 15° to about 25°.

Interaction between actuation sled 510 and staple pusher 160 (FIG. 6) ofstaple drive assembly 500 is shown in FIGS. 50-51 and discussed indetail hereinafter. Initially, as illustrated in FIG. 50, actuation sled510 translates distally through staple cartridge 40′ in the directionindicated by arrow A causing first drive face 522 a to slidably engagefirst cam surface 162 b and urge staple pusher 160 from its first orrest position in a generally vertical direction as indicated by arrow B.Substantially simultaneously, first drive face 524 a slidably engagesfirst cam surface 16 b thereby urging staple pusher 160 in a generallyvertical direction as indicated by arrow B. Since cam surfaces 162 b,164 b and first drive faces 522 a, 524 a are longitudinally offset,staple pusher 160 is driven in a balanced manner to minimize tipping ortilting of staple pusher 160 as it is driven through retainer slot 60.First drive faces 522 a, 524 a and respective first cam surfaces 162 b,164 b have complementary angles that maximize translation oflongitudinal motion of actuation sled 510 to vertical motion of staplepusher 160.

Referring now to FIG. 51, continued distal movement of actuation sled510 further urges staple pusher 160 generally vertically to anintermediate position, such that second drive faces 522 b, 524 bslidably engage respective second cam surfaces 162 a, 164 b while firstdrive faces 522 a, 524 a substantially simultaneously disengage fromrespective first cam surfaces 162 b, 164 b. Similarly, second drivefaces 522 b, 524 b and respective second cam surfaces 162 a, 164 a havecomplementary angles to maximize translation of longitudinal motion ofactuation sled 510 to vertical motion of staple pusher 160. Continuingdistal movement of actuation sled 510 continues to urge staple pusher160 vertically to its second or end position immediately prior to thedisengagement between second drive faces 522 b, 524 b and respectivesecond cam surfaces 162 a, 164 a.

Since the interaction between second camming member 540 and staplepusher 160 is substantially identical to the intersection of firstcamming member 520 and pusher 160, the intersection of second cammingmember 540 and staple pusher 160 will not be described in detail herein.

Longitudinal motion of actuation sled 510 in the direction indicated byarrow A results in first and second camming members 520, 540 slidablyengaging staple pushers 160 as shown in FIGS. 50-51. Sliding engagementbetween leading cam wedges 522, 542 and second cam members 164 incooperation with the substantially simultaneous engagement betweentrailing cam wedges 524, 544 and first cam members 162 improve thelongitudinal stability of the staple pushers 160 during vertical motionas follows. Leading cam wedges 522, 542 are longitudinally spaced apartfrom trailing cam wedges 524, 544 by a predetermined amount. Sincerespective first and second cam members 162, 164 are longitudinallyspaced apart by a comparable, but complementary amount, longitudinalmovement of actuation sled 510 results in the substantially simultaneousengagement of leading cam wedges 522, 524 and trailing cam wedges 524,544 with respective first and second cam members 162, 164 therebytransferring the longitudinal movement of actuation sled 510 to verticalmovement of staple pusher 160 at longitudinally spaced apart impactpoints. By transferring longitudinal movement of actuation sled 510 toeach staple pusher 160 at two longitudinally spaced apart impact points,substantially balanced vertical movement of each staple pusher 160 isachieved. Since there is two point contact between first and secondcamming members 520, 540 and respective first and second cam members162, 164 throughout the vertical travel of each staple pusher 160,pivoting or tilting of each staple pusher 160 is minimized due to thetwo-point contact arrangement. Minimizing pivoting or tilting of eachstaple pusher 160 during vertical travel further minimizes pivoting ortilting of each staple 50 as each staple 50 is driven vertically in itsrespective retention slot 60. This provides more precise contact of astaple with an anvil pocket (not shown) and thus, improved stapleformation.

Interaction between actuation sled 510 and staple pushers 260, 360 issubstantially similar to the interaction described hereinabove betweenactuation sled 510 and staple pusher 160 and will not be discussed indetail. It is sufficient to note that staple pushers 260, 360 may befreely substituted for staple pusher 160.

Further embodiments of the present disclosure are illustrated in FIGS.52-56 and discussed in detail hereinafter. The embodiments that areillustrated in FIGS. 52-56 include a cam member or actuation bar. Anexample of a suitable cam bar and associated apparatus is disclosed inU.S. Pat. No. 6,619,529 to Green et al., currently owned by TycoHealthcare Group LP, the contents of which are hereby incorporated byreference in their entirety. In addition, the staple cartridge 40′ (FIG.3) may include longitudinal slots as disclosed in the '529 for providinglateral stability to the cam bars as they translate longitudinallythrough staple cartridge 40′. Referring initially to FIG. 52, a portionof a cam bar or actuation member 600 is illustrated. Actuation member600 includes a distal end 610 wherein distal end 610 includes the sameor substantially similar components as included in actuation sled 110(FIG. 11). Distal end 610 includes a base 612, a first camming member620, and a second camming member 640 (not shown). First and secondcamming members 620, 640 include respective first or leading cam wedges622, 642 and respective second or trailing cam wedges 624, 644. Theconfiguration and relationships between the components of distal end 610are substantially similar to those components of actuation sled 110 andwill not be described in detail herein. Essentially, distal end 610includes actuation sled 110 using reference characters 6 xx in lieu of 1xx used in describing actuation sled 110. In addition, actuation member600 and distal end 610 may be substituted for actuation sled 110 instaple cartridge 40′ (FIG. 4). The interaction of distal end 610 andstaple pusher 160 (FIG. 6) is substantially similar to the interactionof actuation sled 110 and staple pusher 160 (see FIGS. 16-17) and willnot be discussed in detail herein. Further still, distal end 610 isadapted to cooperate with staple pusher 260 (FIG. 26) or staple pusher360 (FIG. 28). As shown, cam wedges 622, 642 are laterally andlongitudinally offset and engage corresponding surfaces on the staplepusher (not shown) for improving the stability of the staple pusherduring firing, as described above with respect to cam wedges 122, 142.

In FIG. 53, a portion of an actuation member 700 is shown and includes adistal end 710 having the same or substantially similar components asincluded in actuation sled 210 (FIG. 19). Distal end 710 includes a base712, a first camming member 720, and a second camming member 740 (notshown). First and second camming members 720, 740 include respectivefirst or leading cam wedges 722, 742 and respective second or trailingcam wedges 724, 744. The configuration and relationships between thecomponents of distal end 710 are substantially similar to thosecomponents of actuation sled 210 and will not be described in detailherein. Essentially, distal end 710 includes actuation sled 210 usingreference characters 7 xx in lieu of 2 xx used in describing actuationsled 210. In addition, actuation member 700 and distal end 710 may besubstituted for actuation sled 210 in staple cartridge 40′. Theinteraction of distal end 710 and staple pusher 160 (FIG. 6) issubstantially similar to the interaction of actuation sled 210 andstaple pusher 160 (see FIGS. 22-23) and will not be discussed in detailherein. Further still, distal end 710 is adapted to cooperate withstaple pusher 260 (FIG. 26) or staple pusher 360 (FIG. 28). In thisembodiment, the lateral and longitudinal offset of the cam wedges areenhanced by providing drive surfaces wherein the first drive angle isless than the second drive angle. This arrangement of drive anglesenhances staple pusher stability, thereby minimizing tilting or rotationand further reduces uneven firing of staples 50.

FIG. 54 illustrates a portion of an actuation member 800 and includes adistal end 810 having the same or substantially similar components asactuation sled 310 (FIG. 30). Distal end 810 includes a base 812, afirst camming member 820, and a second camming member 840 (not shown).First and second camming members 820, 840 include respective first orleading cam wedges 822, 842 and respective second or trailing cam wedges824, 844. The configuration and relationships between the components ofdistal end 810 are substantially similar to those components ofactuation sled 310 and will not be described in detail herein.Essentially, distal end 810 includes actuation sled 310 using referencecharacters 8 xx in lieu of 3 xx used in describing actuation sled 310.In addition, actuation member 800 and distal end 810 may be substitutedfor actuation sled 310 in staple cartridge 40′. The interaction ofdistal end 810 and staple pusher 160 (FIG. 6) is substantially similarto the interaction of actuation sled 310 and staple pusher 160 (seeFIGS. 35-36) and will not be discussed in detail herein. Further still,distal end 810 is adapted to cooperate with staple pusher 260 (FIG. 26)or staple pusher 360 (FIG. 28). In this embodiment, the lateral andlongitudinal offset of the cam wedges improves the stability of thestaple pusher during firing.

FIG. 55 illustrates a portion of an actuation member 900 and includes adistal end 910 having the same or substantially similar components asactuation sled 410 (FIG. 37). Distal end 910 includes a base 912, afirst camming member 920, and a second camming member 940 (not shown).First and second camming members 920, 940 include respective first orleading cam wedges 922, 942 and respective second or trailing cam wedges924, 944. The configuration and relationships between the components ofdistal end 910 are substantially similar to those components ofactuation sled 410 and will not be described in detail herein.Essentially, distal end 910 includes actuation sled 410 using referencecharacters 9 xx in lieu of 4 xx used in describing actuation sled 410.In addition, actuation member 900 and distal end 910 may be substitutedfor actuation sled 410 in staple cartridge 40′. The interaction ofdistal end 910 and staple pusher 460 (FIG. 42A) is substantially similarto the interaction of actuation sled 410 and staple pusher 460 (seeFIGS. 43-44) and will not be discussed in detail herein.

FIG. 56 illustrates a portion of an actuation member 1000 and includes adistal end 1010 having the same or substantially similar components asactuation sled 510 (FIG. 45). Distal end 1010 includes a base 1012, afirst camming member 1020, and a second camming member 1040 (not shown).First and second camming members 1020, 1040 include respective first orleading cam wedges 1022, 1042 and respective second or trailing camwedges 1024, 1044. The configuration and relationships between thecomponents of distal end 1010 are substantially similar to thosecomponents of actuation sled 510 and will not be described in detailherein. Essentially, distal end 1010 includes actuation sled 510 usingreference characters 10 xx in lieu of 5 xx used in describing actuationsled 510. In addition, actuation member 1000 and distal end 1010 may besubstituted for actuation sled 510 in staple cartridge 40′. Theinteraction of distal end 1010 and staple pusher 160 (FIG. 6) issubstantially similar to the interaction of actuation sled 510 andstaple pusher 160 (see FIGS. 50-51) and will not be discussed in detailherein. Further still, distal end 1010 is adapted to cooperate withstaple pusher 260 (FIG. 26) or staple pusher 360 (FIG. 28).

FIGS. 57-67 illustrate further embodiments of the present disclosure. Inone embodiment, a staple cartridge 2140 includes a tissue contactingportion 2161. As seen in FIG. 57, tissue contacting portion 2161includes first, second, and third tissue contacting surfaces 2161 a,2161 b, 2161 c. Specifically, tissue contacting surfaces 2161 a-2161 care planar structures that are substantially parallel to one another,but are not co-planar with one another (i.e. the tissue contactingportion is stepped). A set of tissue contacting surfaces 2161 a-c isdisposed on each side of knife channel 2148. The third tissue contactingsurfaces 2161 c have a knife channel 2148 defined therein. The tissuecontacting surfaces 2161 c are co-planar with one another. The first,second, and third tissue contacting surfaces 2161 a, 2161 b, 2161 c havedifferent heights as measured from knife channel 2148. Additionally,each first tissue contacting surface 2161 a is co-planar with oneanother. Similarly, each second tissue contacting surface 2161 b isco-planar with one another. Although the drawings show planar tissuecontacting surfaces 2161 a-2161 c, the present disclosure envisionscurved or angled tissue contacting surfaces as well as other kinds oftissue contacting surfaces having other shapes and structures.

A wall or any other suitable structure interconnects first and secondtissue contacting surfaces 2161 a and 2161 b. Similarly, a suitablestructure such as a wall interconnects second and third contactingsurfaces 2161 b and 2161 c. The walls or interconnecting structures maybe oriented orthogonally with respect to the tissue contacting surfaces2161 a-216 c. The present disclosure, however, contemplates walls orinterconnecting structures oriented in different directions such asangled, curved or other configurations.

In an embodiment, first tissue contacting surface 2161 a has the leastheight, third tissue contacting surface 2161 c has the greatest height,and second tissue contacting surface 2161 b has a height between theheights of first and third tissue contacting surfaces 2161 a, 2161 c.While tissue contacting surfaces 2161 a-2161 c are shown as decreasingin height from first tissue contacting surface 2161 a to third tissuecontacting surface 2161 c, it is envisioned that the heights of eachtissue contacting surface may vary depending on the particular surgicalprocedure. Other features of tissue contacting surfaces 2161 a-2161 cmay also vary according to the circumstances.

Each tissue contacting surface 2161 a-2161 c includes a plurality ofretention slots 2144 formed therein. Retention slots 2144 are disposedin a plurality of rows 2144 a, 2144 b, 2144 c that are located in tissuecontacting surfaces 2161 a, 2161 b, 2161 c respectively. The linear rowsof retention slots 2144 a-c are staggered along the longitudinal axis ofstaple cartridge 2140 as shown in FIGS. 57 and 67. Particularly, thedistal most retention slots 2144 of rows 2144 a, 2144 c are closer tothe distal end of cartridge 2140 than the distal most retention slots2144 of row 2144 b. On the other hand, the most proximal retention slots2144 of rows 2144 b are closer to the proximal end of cartridge 2140than the most proximal retention slots 2144 of rows 2144 a, 2144 c.Linear rows of retention slots 2144 a-2144 c having other suitablearrangements are within the scope of the present disclosure as long asthey are capable of receiving surgical fasteners.

FIG. 57 a illustrates an arrangement of the surgical fasteners 50 a-c inthe staple cartridge 2140. Staple cartridge 2140 includes surgicalfasteners or staples 50 a, 50 b, and 50 c. Each staple 50 a, 50 b, and50 c includes a backspan 52 a-c. Legs 55 a of surgical fasteners 50 ahave a first leg length “A”, legs 55 b of surgical fasteners 50 b have asecond leg length “B”, and legs 55 c of surgical fasteners 50 c have athird leg length “C.” In one embodiment, first length “A” is greaterthan second length “B.” In turn, second length “B” is greater than thirdlength “C.” U.S. Patent Application Publication No. 2007/0131732, theentire contents of which is incorporated by reference herein, describesan embodiment of the disclosed fastener arrangement. The presentdisclosure, however, contemplates other fastener arrangements. Surgicalfasteners 50 a-c are configured to operate in conjunction with staplepusher 2160.

Surgical fasteners 50 a-c cooperate with staple pusher 2160 and sled 110(FIG. 61) such that the longitudinal translation of sled 110 throughstaple cartridge 2140 urges pushers 2160 in a vertical direction toeject surgical fasteners 50 a-c. As shown in FIG. 57 a, staple pusher2160 includes pusher plates 2166 a-c, each of which has a differentvertical dimension. Pusher plate 2166 c has the greatest verticaldimension and cooperates with surgical fastener 50 c, which has thesmallest leg length. Pusher plate 2166 a has the smallest verticaldimension and cooperates with surgical fastener 50 a, which has thelargest leg length. Pusher plate 2166 b has a vertical dimension greaterthan pusher plate 2166 a, but less than pusher plate 2166 c andcooperates with surgical fastener 50 b, which has an intermediate leglength, between those of surgical fasteners 50 a and 50 c. The surgicalfasteners 50 c are arranged adjacent knife channel 2148. Surgicalfasteners 50 a are adjacent to outer edge of cartridge 2140, andsurgical fasteners 50 b are disposed therebetween. By providing surgicalfasteners 50 a-c and pusher plates 2160 with complementary heights, thevarious sized-staples are formed against the anvil of the stapler, intothe desired shape. It is also envisioned that other arrangements ofpusher plates and surgical fasteners may be used.

In tool assemblies according to the present disclosure, staples havingdifferent leg lengths may be arranged so that the staples with thelarger leg lengths are arranged adjacent the knife channel 2148. Inaddition, the staple cartridge 2140 may have a single planar tissuecontacting surface and the anvil member may be provided with more thanone tissue contacting surface so as to define more than one gap withrespect to the tissue contacting surface of the staple cartridge. One orboth of the staple cartridge and anvil member may have stepped surfaces,angled or sloped surfaces, or curved surfaces that are selected tocorrespond to staples having predetermined leg lengths. In certainembodiments, more than one tissue contacting surface is provided, on thestaple cartridge, the anvil member, or both, with sloped surfacesextending therebetween. In certain embodiments, the staple pushers haveheights corresponding to the different staple sizes. The anvil pocketsof the anvil assembly, the staple pushers, and/or the actuation sled arearranged to form each of the different sized staples in the desiredclosed shapes.

In one embodiment, staple cartridge 2140 includes at least one doublestaple pusher 2170, at least one triple staple pusher 2160 and at leastone quadruple staple pusher 2180. As seen in FIG. 57, double staplepusher 2170 has only two pusher plates 2176, triple staple pusher 2160has three pusher plates 2166, and quadruple staple pusher 2180 has fourpusher plates 2186. The staples and pushers are arranged in a pattern ona first side 2148 a of knife channel 2148 and on a second side 2148 b ofknife channel 2148, so as to form three longitudinal rows of staples oneach side of knife channel 2148.

Double staple pushers 2170 are disposed at the proximal end of staplecartridge 2140 and are adapted to deploy the most proximal staples 50 band 50 c through retention slots 2144 of rows 2144 b and 2144 c,respectively. One double staple pusher 2170 interacts with two mostproximal staples 50 b and 50 c disposed in retention slots 2144 of rows2144 b and 2144 c. Quadruple staple pushers 2180 are positioned in thedistal end of staple cartridge 2140 and are configured to deploy four ofthe distal most staples 50 a and 50 c, including the staples which aredeployed through the distal most retention slots 2144 of rows 2144 c,2144 a. The quadruple staple pushers 2180 interact with another staple50 a in the outermost retention slots 2144 of rows 2144 a, as well as astaple 50 b in retention slots 2144 of rows 2144 b. For each side 2148a, 2148 b of the staple cartridge, one double staple pusher 2170 isdisposed at a proximal end of the staple cartridge 2140 and onequadruple staple pusher 2180 at the distal end of the staple cartridge2140. The pushers are arranged in a mirror-image of each other, ineither side of the staple cartridge.

A plurality of triple staple pushers 2160 extend between double staplepushers 2170 and quadruple staple pushers 2180 in a longitudinal mannerand are configured to deploy the staples 50 a, 50 b and 50 c fromretention slots 2144 of the innermost rows 2144 c, middle rows 2144 b,and outermost rows 2144 a. One triple staple pusher 2160 interacts withone staple 50 a disposed in retention slot 2144 of the outermost row2144 a, one staple 50 b disposed in retention slot 2144 of rows 2144 b,and one staple 50 c disposed in retention slot 2144 of the innermost row2144 c. The pusher plates of the triple staple pushers 2160 have heightsthat corresponds to the size of the staples, as discussed above.

Referring now to FIGS. 58-61, each double staple pusher 2170 includes afirst cam member 2172, a second cam member 2174, a first prong or pusherplate 2176, and a second pusher plate 2178. Pusher plate 2176 isdisposed on an innermost portion of double staple pusher 2170 withrespect to knife channel 2148. Moreover, pusher plate 2176 is positionedon distal most end of staple pusher 2170. As seen in FIG. 60, pusherplate 2176 is substantially parallel to a longitudinal axis of staplecartridge 2140 and substantially parallel to axis “L.” In addition,pusher plate 2176 includes a leading edge 2176 a and a trailing edge2176 b. Further, each pusher plate 2176 includes a top surface 2176 cadapted for releasably engaging backspan 52 c of staple 50 c (see FIG.57 a). The most proximal retention slot 2144 in the innermost row 2144 cis configured for releasably receiving staple 50 c and pusher plate2176. As discussed above, double staple pusher 2170 also includes asecond pusher plate 2178. Pusher plate 2178 is disposed on the proximalend of double staple pusher 2170 and on the outermost portion of doublestaple pusher 2170 with respect to knife channel 2148. As seen in FIG.60, pusher plate 2178 is substantially parallel to a longitudinal axisdefined along staple cartridge 2140 and substantially parallel to axis“L.” Pusher plate 2178 includes a leading edge 2178 a and a trailingedge 2178 b. Each pusher plate 2178 includes a top surface 2178 cadapted for releasably engaging backspan 52 b of staple 50 b (see FIG.57 a). The most proximal retention slot 2144 in the intermediate row2144 b is configured for releasably receiving staple 50 b and pusherplate 2178.

In addition to first and second pusher plates 2176, 2178, double staplepusher 2170 has first and second cam members 2172, 2174 that aresubstantially parallel to an axis “L”, as seen in FIG. 60. First andsecond cam members 2172, 2174 lie in a plane parallel to a longitudinalaxis of staple cartridge 2140 and include respective first and secondcam surfaces 2172 a, 2172 b, and 2174 a, 2174 b (see FIGS. 59 and 61).Transition points 2172 c, 2174 c are located at the intersection of camsurfaces 2172 a, 2172 b and 2174 a, 2174 b. A plane “O” extendingthrough transition point 2172 c, 2174 c is parallel to tops 2173, 2175overlying the cam surfaces (see FIGS. 59 and 61). In one embodiment,first cam surfaces 2172 a, 2174 a define a first engagement or receivingangle with respect to tops 2173, 2175 of respective first and second cammembers 2172, 2174. Second cam surfaces 2172 b, 2174 b define a secondengagement or receiving angle with respect to plane “O.” Since theinteraction of sled 110 and cam surfaces 2172 a, 2172 b and 2174 a, 2174b is substantially identical to the interaction of sled 110 and camsurfaces 162 a, 162 b and 164 a, 164 b, the interaction of sled 110 andcam surfaces 2172 a, 2172 b and 2174 a, 2174 b will not be describedherein in detail.

A quadruple staple pusher 2180 is shown in FIGS. 62-66. Each quadruplestaple pusher 2180 includes a first cam member 2182, a second cam member2184, at least four prongs or pusher plates 2186 a, 2186 b, 2186 c, 2186d. Pusher plates 2186 b-2186 d are laterally and longitudinally spacedapart from each other. Pusher plate 2186 a is longitudinally alignedwith, but laterally offset from 2186 b. Pusher plate 2186 c is laterallyspaced between distal pusher plates 2186 a and 2186 b and is axiallyoffset in the proximal direction from distal pusher plates 2186 a and2186 b. An outboard (with respect to knife channel 2148) proximal pusherplate 2186 d is laterally spaced apart from middle pusher plate 2186 cand is axially offset in the proximal direction from middle pusher plate2186 c. Each pusher plate 2186 a-d is substantially parallel to alongitudinal axis of staple cartridge 2140 and parallel to axis “I,” asseen in FIG. 65. Pusher plates 2186 a-b are most-distal along axis “I.”In addition, each pusher plate 2186 a-d includes a leading edge 2187 anda trailing edge 2189. In one embodiment, pusher plates 2186 a-d may belongitudinally spaced apart or staggered such that the longitudinalspacing between leading edges 2187 of adjacent pusher plates 2186 a-c isabout two-thirds the length of distal retention slot 2144 of row 2144 c.Further still, each pusher plate 2186 a-d includes a top surface 2181that is adapted for releasably engaging a backspan 52 a-c of staple 50a-c (see FIG. 57 a). The distal most retention slots 2144 of rows 2144a-c are configured for releasably receiving staples 50 a-c and pusherplates 2186 a-d. Overall, quadruple staple pusher 2180 is configured todeploy four staples, including two most distal staples 50 a in retentionslots 2144 of rows 2161 a, one most distal staple 50 b in retention slot2144 of row 2161 b and one most distal staple 50 c in retention slot2144 of rows 2161 c. Each pusher plate 2186 may have different verticaldimensions to correspond to the size of the staple. In one embodiment,distal pusher plate 2186 a has the largest vertical dimension and isdesigned to eject staple 50 c. Distal pusher plate 2186 b and outboardpusher plate 2186 d have the smallest vertical dimension and are adaptedto eject staples 50 a. Lastly, middle or intermediate pusher plate 2186c has a vertical dimension less than distal pusher plate 2186 a, butgreater than distal and proximal outboard pusher plates 2186 b, 2186 dand is configured to eject staple 50 b.

In addition, each quadruple staple pusher 2180 includes first and secondcam members 2182, 2184 interposed between adjacent pusher plates 2186a-d as discussed hereinabove. First and second cam members 2182, 2184lie in a plane parallel to a longitudinal axis of staple cartridge 2140.As depicted in FIG. 65, first and second cam members 2182, 2184 are alsosubstantially parallel to axis “I.” Further still, first cam member 2182is disposed between the innermost (with respect to knife channel 2148)distal pusher plate 2186 a and middle pusher plate 2186 c while secondcam member 2184 is disposed between middle pusher plate 2186 c andinboard pusher plate 2186 d. First and second cam members 2182, 2184include respective first and second cam surfaces 2182 a, 2182 b and 2184a, 2184 b (see FIGS. 63, 64 and 66). Transition points 2182 c, 2184 care located at the intersection of first and second cam surfaces 2182 a,2182 b and 2184 a, 2184 b. As seen in FIG. 66, a plane “P” extendingthrough transition points 2182 c, 2182 c is parallel to tops 2183, 2185.In one embodiment, first cam surfaces 2182 a, 2184 a defines a firstengagement or receiving angle with respect to tops 2183, 2185 ofrespective first and second cam members 2182, 2184. Second cam surfaces2182 b, 2182 b define a second engagement or receiving angle withrespect to plane “P.” Since the interaction of sled 110 and cam surfaces2182 a, 2182 b and 2184 a, 2184 b is substantially identical to theinteraction of sled 110 and cam surfaces 162 a, 162 b and 164 a, 164 b,the interaction of sled 110 and cam surfaces 2182 a, 2182 b and 2184 a,2184 b will not be described herein in detail.

In the staple cartridge 2140, the triple staple pushers 2160 arearranged in a row extending longitudinally along the staple cartridge2140, on one side 2148 a of the knife channel 2148, and in another rowon the other side 2148 b of the knife channel 2148. Because of thediagonal shape of the triple staple pushers 2160, each triple staplepusher 2160 nests with adjacent triple staple pushers 2160. The pusherson either side of the staple cartridge 2140 are mirror-images of oneanother, as seen in FIG. 57.

As seen in FIG. 67, an embodiment of the presently disclosed staplecartridge 1140 may alternatively include a single staple pusher 1170instead of a double staple pusher 2170 at the proximal end of the staplecartridge 1140. Single staple pusher 1170 has only one pusher plate1176. Hence, staple cartridge 1140 has one retention slot 1144 less thanstaple cartridge 2140 at the proximal or distal end of the intermediateor middle rows 1144 b. Aside from the difference in the number ofretention slots, staple cartridge 1140 is substantially similar tostaple cartridge 2140.

Staple cartridge 1140 has a tissue contacting portion 1161 includingfirst, second, and third tissue contacting surfaces 1161 a, 1161 b, and1161 c. Tissue contacting surfaces 1161 a-1161 c are planar structuresthat are substantially parallel to one another but are not co-planarwith one another (i.e. stepped). A set of tissue contacting surface 1161a-c is disposed on each side of knife channel 1148. Each third tissuecontacting surface 1161 c is co-planar with knife channel 1148 and withone another. First and second tissue contacting surfaces 1161 a, 1161 bhave different heights as measured from knife channel 1148.Additionally, each first tissue contacting surface 1161 a is co-planerwith each other. Similarly, each second tissue contacting surface 1161 bis coplanar with each other. A wall or any other suitable structureinterconnects first and second tissue contacting surfaces 1161 a and1161 b with each other. Likewise, a wall or any other suitable structureinterconnects second and third tissue contacting surfaces 1161 b and1161 c.

First tissue contacting surface 1161 a has the least height incomparison with second and third tissue contacting surface 1161 b and1161 c. Third tissue contacting surface 1161 c has the greatest height,and second tissue contacting surface 1161 b has a height between theheights of first and third tissue contacting surfaces 1161 a and 1161 c.While tissue contacting surfaces 1161 a-1161 c are depicted asdecreasing in height from first tissue contacting surface 1161 a tothird tissue contacting surface 1161 c, the present disclosurecontemplates tissue contacting surfaces having other heights andarrangements.

Each tissue contacting surface 1161 a-1161 c includes a plurality ofretention slots 1144 formed therein. Retention slots 1144 are disposedin a plurality of rows 1144 a, 1144 b, 1144 c that are located in tissuecontacting surfaces 1161 a, 1161 b, 1161 c, respectively. The linearrows of retentions slots 1144 a-1144 c are staggered along thelongitudinal axis of staple cartridge 1140. Specifically, the distalmost retention slots 1144 of rows 1144 a and 1144 c are closer to thedistal end of the staple cartridge 1140 than the distal most retentionslots 1144 of row 1144 b. In addition, the most proximal retention slots1144 of rows 1144 a and 1144 c are closer to the proximal end ofcartridge 1140 than the most proximal retention slots 1144 of row 1144b.

In particular, the innermost (with respect to knife channel 1148) mostproximal retention slots 1144 of rows 1144 c are adapted to retain atleast a portion of single staple pusher 1170. As illustrated in FIGS.68-72, each single staple pusher 1170 includes a first cam member 1172,a second cam member 1174 and a prong or pusher plate 1176. Pusher plate1176 is substantially parallel to an axis “L” of staple cartridge 1140,as seen in FIG. 71. Pusher plate 1176 includes a leading edge 1176 a anda trailing edge 1176 b. Further, each pusher plate 1176 includes a topsurface 1176 c adapted for releasably engaging the backspan 52 c ofstaple 50 c disposed in retention slots 1144 of rows 1144 c. The mostproximal retention slot 1144 in the rows 1144 c are configured forreleasably receiving staples 50 c and pusher plate 1176.

As previously discussed, pusher plates also includes first and secondcam members 1172, 1174. First and second cam members 1172, 1174 lie in aplane parallel to a longitudinal axis of staple cartridge 1140. Inaddition, first and second cam members 1172, 1174 are substantiallyparallel to axis “L” of each single staple pusher 1170. First and secondcam members 1172, 1174 include first and second cam surfaces 1172 a,1172 b, and 1174 a, 1174 b (see FIG. 70). Transition points 1172 c, 1174c are located at the intersection of cam surfaces 1172 a, 1172 b and1174 a, 1174 b. A plane “O” extending through transition point 1172 c,1174 c is substantially parallel to tops 1173, 1175 of respective firstand second cam members 1172, 1174. Second cam surfaces 1172 b, 1174 bdefine a second engagement or receiving angle with respect to plane O.Since the interaction of sled 110 and cam surfaces 1172 a, 1172 b and1174 a, 1174 b is substantially identical to the interaction of sled 110and cam surfaces 162 a, 162 b and 164 a, 164 b, the interaction of sled110 and cam surfaces 1172 a, 1172 b and 1174 a, 1174 b will not bedescribed herein in detail.

In addition to single staple pusher 1170, staple cartridge 1140 includesa quadruple staple pusher 1180 having at least four pusher plates 1186.Since quadruple staple pusher 1180 is substantially similar to quadruplestaple pusher 2180, the structural features of quadruple staple pusher1180 will not be described herein in detail. Moreover, staple cartridge1140 includes a triple staple pusher 1160 having at least three pusherplates 1166. Since triple staple pusher 1160 is substantially similar totriple staple pushers 2160, the structural features of triple pusher1160 will not be described herein in detail.

While the above description contains many specifics, these specificsshould not be construed as limitations on the scope of the presentdisclosure, but merely as exemplifications of preferred embodimentsthereof. Those skilled in the art will envision many other possiblevariations that are within the scope and spirit of the presentdisclosure. By way of example only, it is contemplated that the driveangles of various surfaces of the cam wedges may differ between camwedges of the same actuation mechanism or that the receiving angles ofthe staple pusher receiving surfaces may differ as between the cammembers of the same staple pusher, or both.

1. A staple drive assembly comprising: a cartridge; an actuation sleddisposed in the cartridge; at least one first staple pusher having twopusher plates, the at least one first pusher being adapted to eject twofastening members and disposed at a proximal portion of the cartridge;at least one second staple pusher having four pusher plates, the atleast one second pusher being adapted to eject fastening members anddisposed at a distal portion of the cartridge; and at least one thirdstaple pusher having three pusher plates, the at least one third pusherbeing adapted to eject a plurality of fastening members and disposed inthe cartridge in between the at least one first staple pusher and the atleast one second staple pusher.
 2. The staple drive assembly of claim 1,wherein the actuation sled includes at least one camming member, the atleast one camming member including spaced apart first and second camwedges, each cam wedge including at least first and second drive faces,the at least first and second drive faces being configured to definefirst and second drive angles with respect to the base wherein the firstdrive angle is less than the second drive angle.
 3. The staple driveassembly of claim 2, wherein the at least one first staple pusherincludes a first and second cam members, each cam member having at leastone engagement surface.
 4. The staple drive assembly of claim 2, whereinthe at least one second staple pusher includes a first and second cammembers, each cam member having at least one engagement surface.
 5. Thestaple drive assembly of claim 2, wherein the at least one third staplepusher includes a first and second cam members, each cam member havingat least one engagement surface.
 6. The staple drive assembly of claim2, wherein the first and second cam wedges are longitudinally andlaterally spaced apart from one another for engaging each cam member. 7.The staple drive assembly of claim 3, wherein each cam member includesfirst and second engagement surfaces defining respective first andsecond receiving angles that are complementary to the respective firstand second drive angles.
 8. The staple drive assembly of claim 4,wherein each cam member includes first and second engagement surfacesdefining respective first and second receiving angles that arecomplementary to the respective first and second drive angles.
 9. Thestaple drive assembly of claim 5, wherein each cam member includes firstand second engagement surfaces defining respective first and secondreceiving angles that are complementary to the respective first andsecond drive angles.
 10. The staple drive assembly of claim 2, whereinthe first drive angle is in a range of about 15° to about 25° and thesecond drive angle is in a range of about 30° to about 40°.
 11. Thestaple drive assembly of claim 2, wherein the first drive angle is about35° and the second drive angle is about 20°.
 12. The staple driveassembly of claim 1, wherein the cartridge includes a stepped tissuecontacting surface.
 13. A staple cartridge, comprising: a plurality ofrows of retention slots; a first staple pusher, the first staple pusherconfigured to interact with at least one staple in a first row ofretention slots; and a second staple pusher, the second staple pusherconfigured to interact with at least two staples in a second row ofretention slots.
 14. The staple cartridge of claim 13, furthercomprising an actuation sled configured to interact with first andsecond staple pushers.
 15. The staple cartridge of claim 14, wherein theactuation sled includes at least one camming member, the at least onecamming member including spaced apart first and second cam wedges, eachcam wedge including at least first and second drive faces, the at leastfirst and second drive faces being configured to define first and seconddrive angles with respect to the base wherein the firs drive angle isless than the second drive angle.
 16. The staple cartridge of claim 15,wherein the first staple pusher includes a first and second cam members,each cam member having at least one engagement surface.
 17. The staplecartridge of claim 16, wherein each cam member includes first and secondengagement surfaces defining respective first and second receivingangles that are complementary to the respective first and second driveangles.
 18. The staple cartridge of claim 15, wherein the second staplepusher includes a first and second cam members, each cam member havingat least one engagement surface.
 19. The staple cartridge of claim 18,wherein each cam member includes first and second engagement surfacesdefining respective first and second receiving angles that arecomplementary to the respective first and second drive angles.
 20. Thestaple cartridge of claim 15, wherein the first drive angle is in arange of about 15° to about 25° and the second drive angle is in a rangeof about 30° to about 40°.
 21. The staple cartridge of claim 13, furthercomprising a stepped tissue contacting surface.
 22. The staple cartridgeof claim 13, wherein the first staple pusher includes first and secondpusher plates.
 23. The staple cartridge of claim 22, wherein the firststaple pusher is positioned at a proximal end of the staple cartridge.24. A staple drive assembly, comprising: a cartridge; an actuation sleddisposed in the cartridge; at least one first staple pusher having onepusher plate, the at least one first staple pusher being adapted toeject one fastening member and disposed at a proximal portion of thecartridge; at least one second staple pusher having four pusher plates,the at least one second staple pusher being adapted to eject at leastfour fastening members and disposed at a distal portion of thecartridge; and at least one third staple pusher having three pusherplates, the at least one third staple pusher being adapted to eject aplurality of fastening members and disposed in the cartridge between theat least one first staple pusher and the at least one second staplepusher.
 25. The staple drive assembly of claim 24, wherein the actuationsled includes at least one camming member, the at least one cammingmember including spaced apart first and second cam wedges, each camwedge including at least first and second drive faces, the at leastfirst and second drive faces being configured to define first and seconddrive angles with respect to the base wherein the first drive angle isless than the second drive angle.
 26. The staple drive assembly of claim25, wherein the at least one first staple pusher includes a first andsecond cam members, each cam member having at least one engagementsurface.
 27. The staple drive assembly of claim 25, wherein the at leastone second staple pusher includes first and second cam members, each cammember having at least one engagement surface.
 28. The staple driveassembly of claim 25, wherein the at least one third staple pusherincludes a first and second cam members, each cam member having at leastone engagement surface.
 29. The staple drive assembly of claim 25,wherein the first and second cam wedges are longitudinally and laterallyspaced apart from one another for engaging each cam member.
 30. Thestaple drive assembly of claim 26, wherein each cam member includesfirst and second engagement surfaces defining respective first andsecond receiving angles that are complementary to the respective firstand second drive angles.
 31. The staple drive assembly of claim 27,wherein each cam member includes first and second engagement surfacesdefining respective first and second receiving angles that arecomplementary to the respective first and second drive angles.
 32. Thestaple drive assembly of claim 28, wherein each cam member includesfirst and second engagement surfaces defining respective first andsecond receiving angles that are complementary to the respective firstand second drive angles.
 33. The staple drive assembly of claim 25,wherein the first drive angle is in a range of about 15° to about 25°.34. The staple drive assembly of claim 25, wherein the cartridgeincludes a stepped tissue contacting surface.
 35. A staple driveassembly comprising: a cartridge; an actuation sled disposed in thecartridge; at least one first staple pusher adapted to eject onefastening member and disposed at a proximal portion of the cartridge; atleast one second staple pusher having four pusher plates, the at leastone second staple pusher being adapted to eject at least four fasteningmembers and disposed at a distal portion of the cartridge; and at leastone third staple pusher having three pusher plates, the at least onethird staple pusher being adapted to eject a plurality of fasteningmembers and disposed in the cartridge between the at least one firststaple pusher and the at least one second staple pusher.
 36. The stapledrive assembly of claim 35, wherein the at least one first staple pusherincludes two pusher plates.
 37. The staple drive assembly of claim 35,wherein the at least one first staple pusher includes one pusher plate.38. A staple drive assembly comprising: a cartridge; an actuation sleddisposed in the cartridge; a first staple pusher disposed at a proximalportion of the cartridge; a second staple pusher disposed at a distalportion of the cartridge; and a third staple pusher disposed in betweenthe first staple pusher and the second staple pusher, the third staplepusher having three pusher plates, the first staple pusher having fewerthan three pusher plates, and the second staple pusher having greaterthan three pusher plates.
 39. The staple drive assembly of claim 38,wherein the first staple pusher has two pusher plates adapted to ejecttwo staples.
 40. The staple drive assembly of claim 38, wherein thefirst staple pusher has one pusher plate adapted to eject one staple.41. The staple drive assembly of claim 38, wherein the second staplepusher has four pusher plates adapted to eject four staples.
 42. Thestaple drive assembly of claim 38, wherein the third staple pusher hasthree pusher plates that are longitudinally offset from one another. 43.The staple drive assembly of claim 38, wherein the actuation sledincludes at least one camming member, the at least one camming memberincluding spaced apart first and second cam wedges, each cam wedgeincluding at least first and second drive faces, the at least first andsecond drive faces being configured to define first and second driveangles with respect to the base wherein the first drive angle is lessthan the second drive angle.
 44. The staple drive assembly of claim 43,wherein the at least one first staple pusher includes a first and secondcam members, each cam member having at least one engagement surface. 45.The staple drive assembly of claim 43, wherein the at least one secondstaple pusher includes a first and second cam members, each cam memberhaving at least one engagement surface.
 46. The staple drive assembly ofclaim 43, wherein the at least one third staple pusher includes a firstand second cam members, each cam member having at least one engagementsurface.
 47. The staple drive assembly of claim 43, wherein the firstand second cam wedges are longitudinally and laterally spaced apart fromone another for engaging each cam member.
 48. The staple drive assemblyof claim 47, wherein each cam member includes first and secondengagement surfaces defining respective first and second receivingangles that are complementary to the respective first and second driveangles.
 49. The staple drive assembly of claim 48, wherein each cammember includes first and second engagement surfaces defining respectivefirst and second receiving angles that are complementary to therespective first and second drive angles.
 50. The staple drive assemblyof claim 46, wherein each cam member includes first and secondengagement surfaces defining respective first and second receivingangles that are complementary to the respective first and second driveangles.
 51. The staple drive assembly of claim 38, wherein the cartridgeincludes a stepped tissue contacting surface.
 52. A staple driveassembly comprising: a cartridge; an actuation sled disposed in thecartridge; at least one first staple pusher adapted to eject at leastone staple and disposed at a proximal portion of the cartridge; at leastone second staple pusher having four pusher plates, the at least onesecond staple pusher being adapted to eject at least four staples anddisposed at a distal portion of the cartridge; and at least one thirdstaple pusher having three pusher plates, the at least one third staplepusher being adapted to eject a plurality of staples and disposed in thecartridge between the at least one first staple pusher and the at leastone second staple pusher.
 53. The staple drive assembly of claim 52,wherein the at least one first staple pusher includes two pusher plates.54. The staple drive assembly of claim 52, wherein the at least onefirst staple pusher includes one pusher plate.
 55. A staple driveassembly comprising: a cartridge; an actuation sled disposed in thecartridge; and a plurality of staple pushers, at least one of the staplepushers having four pusher plates including two distal pusher plates, amiddle pusher plate laterally spaced between the distal pusher platesand axially offset from the distal pusher plates, and a proximal pusherplate.
 56. The staple drive assembly of claim 55, wherein at least twoof the pusher plates have different heights.
 57. The staple driveassembly of claim 56, wherein the cartridge has a stepped tissue contactsurface.
 58. The staple drive assembly of claim 55, wherein at least oneof the staple pushers has three pusher plates.
 59. The staple driveassembly of claim 58, wherein the three pusher plates includes a distalpusher plate, a middle pusher plate, and a proximal pusher plate. 60.The staple drive assembly of claim 59, wherein the three pusher platesare laterally and longitudinally offset from one another.
 61. The stapledrive assembly of claim 60, wherein at least two of the pusher plateshave different heights.
 62. The staple drive assembly of claim 55,wherein the staple pushers include a first triple staple pusher and asecond triple staple pusher, the at least one of the staple pushershaving four pusher plates being disposed at a distal portion of thecartridge.